A plate spring has conventionally been known to be used in an electric contact or the like which utilizes the elastic force of the plate spring. Examples of various electronic components including such an electric contact include battery boxes and piezo buzzers.
Button type or coin type cells, which are often used in small electronic devices (e.g., mobile terminals, watches, clinical thermometers, and the like), are in the shape of a button or a coin and configured such that: a housing can, in the form of a cylinder with a closed end, serves as a positive electrode; and a closure can that covers the opening of the housing can (positive electrode) serves as a negative electrode. One example of a known structure to attach such a button type or coin type cell is a coin type cell holding structure as disclosed in Patent Literature 1.
As illustrated in (a) of FIG. 6, a holding mechanism 100 disclosed in Patent Literature 1 includes a circuit board 110, a coin type cell 120, and a positive connection terminal 130 which is provided in a three-dimensional manner. The coin type cell 120 is sandwiched and held by a negative connection terminal 111 on the circuit board 110 and the positive connection terminal 130 such that the coin type cell 12 has some space between itself and the circuit board 110. The coin type cell 120 is made up of a positive housing can 121 and a negative closure can 122. The circuit board 110 includes: a negative electrode contact spring portion 111 (plate spring) that makes pressure contact with the back face (negative closure can 122) of the coin type cell 120; and a positive power source land 112. The positive connection terminal 130 includes a contact spring portion 131 (plate spring) that makes pressure contact with the central portion of the positive housing can 121 of the coin type cell 120; and a conductive spring portion 132 that extends so as to hold the side face of the coin type cell and to make contact with the positive power source land 112 on the circuit board 110.
In the holding mechanism 100 arranged as described above, the cell is mechanically pressed by the metal plate springs having a spring property, and thus the holding mechanism 100 is capable of preventing momentary contact failure between the terminals and the cell in case of movement of the cell due to vibration or the like.
On the other hand, piezo buzzers are used in various electronic devices, and are arranged to generate sound by causing a piezoelectric element bonded to a diaphragm to deform and allowing the diaphragm to vibrate. There are various proposals for the structure of such a piezo buzzer. For example, Patent Literature 2 discloses a piezo buzzer that is structured to eliminate the need for a soldering process and to reduce production cost.
Specifically, as illustrated in (b) of FIG. 6, the piezo buzzer 200 disclosed in Patent Literature 2 includes: a diaphragm 220 with a piezoelectric element 210 bonded to one face thereof; an outer case 230 that is made of resin and that holds the diaphragm 220; and a metal terminal 240, serving as a plate spring, which has been formed together with the outer case 230 through insert molding. The metal terminal 240 is bent up from the bottom of the outer case 230, and is arranged to press one end portion thereof against the piezoelectric element 210 using the elastic force caused by the spring property, thereby forming an electric contact. The piezo buzzer 200 further includes another metal terminal 250. The metal terminal 250 has also been formed together with the outer case 230 through insert molding and is arranged to partially contact the diaphragm 220. The piezo buzzer 200 arranged like this does not necessitate a soldering process.